1. Field of the Invention
This invention relates to the determination of the distance from a primary location to the location of the nearby object. More particularly, it relates to the use of a radio-frequency ranging signal to obtain the distance from the primary location to a transponder located nearby.
2. Background Information
For the measurement of relatively short ranges, laser ranging devices are the most commonly used. However, these devices are too cumbersome and expensive for many applications. Also they are unsuitable for use in situations where simultaneous measurement of ranges to multiple objects is desired. Further, optical signals can be obscured by foliage or other optically intervening objects, or greatly diminished by fog. The present invention is a response to these shortcomings.